Telephone system



J. w. MccLEw 2,020,953

TELEPHONE SYSTEM Filed April 26, `19:54

Nov. 12, 1935.

Z'SheetS-Sheet 1 v INVENTOR- c/aH/v W/u/'AM MgCl/5W Arr-r.'

Nov. 12, 1935. 1 w, MCLE-w 2,020,953

A TELEPHONE SYSTEM Filed April 26, 1 934 2 Sheets-Sheet 2 Patented Nov. 12, 1935 UNITED STATES 2,020,953 TELEPHONE SYSTEM John William McClew,

Liverpool, England, as-

signor to Associated Telephone and Telegraphl Company, Chicago, Ill., `a corporation of Dela- Wavre Application April 26, 1934, Serial N0.'722,589 In Great Britain May 2, 1933 8 Claims.

The present invention relates to telephone or like systems and is more particularly concerned with impulse repeaters for use in such systems which respond to impulses of one type and retransmit impulses of a different type, for instance which convert alternating current impulses into `direct current impulses. The chief object of the invention is the production oi an impulse repeater suitable for terminating a phantomed junction line which shall respond to alternating current impulses of comercial frequency and re-transmit impulses suitable for operating automatic switches and also impulses for eiiecting control operations such as trunk offering.

According to one feature of the invention in an impulse repeater for use in telephone or like systems incoming impulses of one type are adapted to be converted into impulses of a different Itype the character of which varies dependent on the number of trains of impulses which have been transmitted to the repeater independently of the length of individual incoming impulses.

According to another feature of the invention in an impulse repeater for use in telephone or like systems incoming impulses of alternating icurrent are converted into impulses of direct current differing in character for different trains of impulses independently of the length of individual incoming impulses and independently of any signal received from other equipment.

With reference to the expression train of im-r pulses, it should be explained that an impulse is considered to belong to a fresh train of impulses if a certain minimum period has elapsed since the sending of the preceding impulse and from this it follows that a train may consist of only one impulse. Y

' vThe invention will be better understood from the Vfollowing description of one method of carrying it into effect, reference being had to the accompanying drawings comprising Figs. l .and 2 which should be arranged side by side to form a complete circuit. t

Considering now the detailed circuit operation, when the impulse repeater shown is taken into use over the junction line conductors l and ll, a preliminary seizing pulse of alternating current of commercial frequency is extendedpforward over the junction from the distant o ice and is repeated by induction over the repeating coil RPC to operate the alternating current relay AC which may be suitably tuned or may be an ordinary direct Fcurrent relay shunted by a dry rectier. The phantom circuit tapping from the repeating coil RPCVis shown extending from the centre point of the left-hand winding. Relay AC operates relay` A and this in turn energizes relay B. Relay B thereupon locks by Way of its armature u bl, and at armatures b2 and b3 preparesthe loop "5 circuit for the incoming `selector which includes the Winding of the impedance I connected in series with the line winding of the shunt ield relay D. At the end of the preliminary seizing pulse, relays AC and A restore but relay B re- 10 mains operated through armature bl so as to enable armature a2 to complete the operating circuit to the incoming selector, which selector Athereupon connects guarding `earth potential to 1.5,

the release trunk conductor P.

Upon the reception of the rst series of setting impulses which are similar to the seizing impulse, relay AC responds and as before operates relay A, which at armature a2 repeats these impulsesin V the form of interruptions in a direct current loop circuit which serve to set the incoming selecto-r wipers to the required level. Relay C operates through armature a3 with the first pulse, and by reason of its slug and the intermittent energization of its windings remains held throughout the l impulsing period, thereby ,at armatures c2 and c3 disconnecting the calling side of the transmission circuit to prevent distortion of the impulses and at the same time short circuiting the impedance I A and the control winding of relay D to provide a more effective impulsing circuit for the incoming selector. Relay C moreover energizes the driving magnet SPM of the rotary switch which advances its wiper SPB into position 2. It should be explained that the rotary switch is very small and economical to manufacture and comprises essentially a coil similar to .an ordinary telephone relay, which in addition to the usual sets of contact springs is provided with a forward drive pawl and ratchet mechanism which rotates a shaft carrying the wiper SPB. v y

Armature al short circuits relay B through the operated armature c6 each time relay A `responds to an impulse, but relay B remains operated durT ing impulsing because of the momentary nature of the individual impulses.

Subsequent series of impulses .are transmitted in the manner described and at the beginning of each separate train the Wiper of the rotary switch is .advanced one step owing to the operation of relay C. The circuit as shown is arranged for the repetition of ve trains of impulses, .at which time the Wiper SPB comes into its 6th position, in

which relay DC is operated on the release of re- 5 lay C. Relay DC locks up at armature del and at armature dc2 prepares-a leg impulsing circuit suitable for transmitting signals for effecting for example cut in on busy connections, toll breakcall. This isV done by theV transmission of a further impulse of alternating current over l the junction which causes the operation of relays VACV and A in the manner previously described. Since' relay DC is now operatedV however, an earth impulse is transmitted over the negative line extending to the automatic trainof switches which serves to operate a differential relay Vin-the controlling switch in the train in order to. set up the cut-in facility. TollV breakdown and re-ring Y are effected by the extension of further impulses ofalternating current over the junction, and` for each impulse received the repeater connects earth to the negative line so Ias to operate the diierential relay in the controlling switch in the train. If the wanted subscriber is idle, when he repliesbattery Vis reversed back over thejtrain of automatic switches and this brings about the operation of thev shunt field relay D which at armature dl operates relay E over itsupper winding. Thereupon at armature e3 a circuit is completed for the slow-to-operate relay DR which in due course opens the circuit of relay E at armature dri.

DR, however, an alternating current impulse is connected to the junction overarmature el andV e2 and this providesanswering supervision for the operator, or alternatively brings about the operation of the calling subscribers meter in the Vcase of an auto-to-auto connection. Y

If the called subscriber wishes to attract the attention of the operatorhe maydo so by icking his switch-hook which results the inter- S/ andRcommon to the whole exchange.

mittent de-energization of relay D. Relay E is momentarily operated `over its lower winding when relay D releases, pending the restoration of timing relay DRfand is again momentarily op- A' erated as explained when relay D reoperates, so thatY impulses of alternating current Yare connected to the junction to recall themanual cnice.:

e At the end of the conversation if the called vparty replaces his receiver rst, a single alternating current impulse is similarly sent to give clearing supervision. When the calling party replaces fhis receiver or the operato-r removes her plug, aV somewhat prolonged clear-down pu1seofalternating current is transmitted over the junction to operate relay AC, which thereupon brings up relays A and Cand the latter as before-short-circuits relay B. The duration of thev releasing -pulse is;

however, considerably in excess of the slow releasing `time of relay B which therefore restores, and at armature b2 and b3 opens the loop to the train of ,automatic switches. V

o Relay B also at armature b5 connects the driving magnet SPM of the rotary switch tothe common lead which connects withthe homing relays The high resistance relay S in the commonset operates Vin, series `with the magnet, and at armature sl brings up relay R which thereupon short-circuits relay S and increases the current in the circuit suiflciently to enable vrthe magnet s PM to energize and advance the wiper SPB on to the next contact. 4Relay S then releases and restores relay R'so that the operation continues During the slow operating time of relayV automatically until the wiper reaches its home position, where off-normal springs NSP operated from a cam on the shaft again open, and. subsequently when the armature spl opens afterthe release of relay R there is no further circuit for relay S and the switch therefore cornesV to rest in the homeV position l Although in the arrangemfnt described the repeater transmits only two kinds of direct current impulses, it will be understood thatV the invention is not limited to this number since further circuit changes could be controlled by the rotary switch and. if necessary, conditions restored for the final trains of impulses to those prevailing initially.

What is claimed is: Y 1. In a telephone or like system, an incoming line and anoutgoing line interconnected through an impulse repeater, means included in said repeater responsive to nnpulses of agiven Ytype received over the incoming line ifcr repeating` of outgoing impulses of a given character, means Vfor counting the trains of impulses as they are received and repeated, and means .controlled ,by

the countingV means for altering the character ofV the repeated impulses.

3. In combination, .an impulse repeater responsive to train of impulses' torepeat-corresponding trains of impulses of a given character, counting means controlled by the impulse trains handled byV the repeater, and means controlled by the counting means for altering. the character ofthe repeated impulses aftera'predetermined number of trains of impulses have been repeated;V

- 4. In an impulse repeater forrepeating a pre- K determined number ofV received trains of impulses to effect successive vswitching operationsxandfor repeating subsequent Vreceived impulses to effect incidental control operations, means for repeating the received trainsas impulses of a given character, means forV counting the trains-of im- ,Y

Vpulses as they are repeated, and means controlled by the counting means when it has counted the predetermined number of impulse trains for altering theV repeater so that subsequently received impulses Yare repeated asV impulses of ai diierent character, whereby the control operations maybe J more readily performed. Y

5. In combination, an impulse repeater responsive to trains of impulses to repeat corresponding trains of impulses of a given character, counting means controlled bythe impulse trainshanrdled by the repeater, means controlled by the counting means for alteringV the character ofthe repeated impulses after a predetermined Vnumber of trains of impulses have been repeated, and means Y responsive to the receiptof a prolonged incoming impulse for restoring said countingrmeans 'at the end of such prolonged impulse.

. 6. InV a telephone system, an incoming telephone line extending to an automatic switchboard Y by way of Van impulse repeater, means inthe re- Y peater responsive to impulses received over said lineior repeating setting impulses to said switchboard, means in said repeater for responding to an answering-supervisory indication and subsequentlyA to a disconnect-supervisory indicationV transmitted thereto from said switchboard,` a

slow-operating and slow-releasing relay in said repeater, and means in said repeater responsive to one received supervisory condition for transmitting a supervisory impulse back over the incoming line of a duration governed by the slowoperating characteristic of said relay and responsive to the other supervisory condition for transmitting a supervisory signal back over the incoming line of ,a duration governed by the slow-releasing characteristic of said relay.

7. In a telephone system, a telephone line eX- tending to a switchboard by way of a repeater, control means in the repeater responsive to the initiation and to the termination of a state of answered supervision controlled through said switchboard, a relay having a slow-operating characteristic and a slow-releasing characteristic, and means operated from the control means on one response thereof to send a supervisory impulse back over said line of a duration controlled by the slow-operating characteristic of said relay and operated from the control means on the other response thereof to send a supervisory impulse back over the said line of a duration controlled by the slow-releasing characteristic of said relay.

8. In a telephone system, a telephone line extending to a switchboard by way of a repeater, control means in said repeater arranged and adapted to operate upon the initiation of and to restore upon the termination of a distinct supervisory state imposed on said line through said switchboard, a relay having a slow-responding characteristic, and means operable under the control of said control means at the initiation of and again upon the termination of said supervisory condition to transmit a supervisory impulse over said line of a duration governed by the slowresponding characteristic of said relay.

JOHN WILLIAM MCCLEW. 

